I do not want to share with anyone especially my family

are they automatically able to see my emails etc

No. All content in a Family Sharing group is private and separate. You share purchased content and the ability to utilise the space available in the iCloud+ subscription - note: the space, but not the content.

As Apple says in What is Family Sharing? When family members join, they get instant access to the group’s subscriptions and content that are eligible for sharing. Each family member uses their own account, so everyone’s experience stays personalized and private.